The term attitude is used in the following description to indicate the orientation of a direction integral with the aircraft with respect to the fixed direction in space.
In the event of the helicopter ditching, it is of fundamental importance to ensure the safe and orderly evacuation of the passengers and crew through the helicopter's emergency exits.
To this end, lighting systems are provided that are designed to indicate the correct path to follow for reaching the emergency exits.
Nevertheless, is has been found that in the event of ditching, human panic can result in confused and irrational behaviour of the helicopter's occupants.
This can cause catastrophic consequences even in cases where the necessary safety equipment, such as lifejackets and floatation systems, are duly present on board the helicopter.
The situation becomes even the more problematic in the case where, after ditching, the helicopter has an upside-down attitude or a half-overturned attitude on the water. In fact, in these circumstances, the helicopter's occupants have difficulty in perceiving the attitude of the helicopter and reaching the emergency exits in an orderly manner.
Moreover, in the event of ditching at night or in conditions of poor visibility, the situation is rendered even more difficult by the fact that the emergency lighting systems intended to indicate the correct route to the emergency exits might have been damaged by the impact upon ditching.
In consequence, the need is felt within the industry to facilitate correctly abandoning the helicopter in the event of it ditching, especially when the helicopter is upside down or resting on one side.
There is particular awareness of above-indicated need in the event of ditching at night or in conditions of poor visibility.
EP-B-0828657 describes an emergency lighting system for a path leading to an emergency exit for an aircraft. The lighting system comprises a pair of photoluminescent strips mounted on the floor, which run along a first direction and are separated from each other to define the path for the aircraft's passengers.
U.S. Pat. No. 6,099,136 describes an emergency escape lighting system, which is chemically activated and placed close to a corner of a helicopter door defining the emergency exit. More specifically, the system comprises two chemical agents, which when mixed together form a compound that radiates light. The agents are stored in a container, which comprises two distinct and separated chambers. When the system is activated, the volume of the chambers is reduced, thereby forcing the agents into a mixing chamber. The compound then flows through a transparent conduit which extends around the escape exit.
US 2010/0193633 describes a lighting system for an aircraft exit. The lighting system is mounted on the floor in a position adjacent to the exit and comprises a light source.
U.S. Pat. No. 7,089,674 discloses a gyroscope and, more particularly, an angle measuring gauge for motorcycles and the like.
US-A-2013/326894 discloses a gradient measuring assembly for use in conjunction with excavating machinery to indicate to a user the slope angle of an excavating vehicle as positioned on a surface being excavated or graded.
FR-A-2838402 discloses an aircraft according to the preamble of claim 1.